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CLN: Put exit_stack inside _query_iterator. #51125

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Merged
merged 1 commit into from
Feb 3, 2023
Merged

CLN: Put exit_stack inside _query_iterator. #51125

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132 changes: 62 additions & 70 deletions pandas/io/sql.py
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Original file line number Diff line number Diff line change
Expand Up @@ -75,14 +75,6 @@
# -- Helper functions


def _cleanup_after_generator(generator, exit_stack: ExitStack):
"""Does the cleanup after iterating through the generator."""
try:
yield from generator
finally:
exit_stack.close()


def _convert_params(sql, params):
"""Convert SQL and params args to DBAPI2.0 compliant format."""
args = [sql]
Expand Down Expand Up @@ -1093,6 +1085,7 @@ def insert(
def _query_iterator(
self,
result,
exit_stack: ExitStack,
chunksize: str | None,
columns,
coerce_float: bool = True,
Expand All @@ -1101,28 +1094,29 @@ def _query_iterator(
):
"""Return generator through chunked result set."""
has_read_data = False
while True:
data = result.fetchmany(chunksize)
if not data:
if not has_read_data:
yield DataFrame.from_records(
[], columns=columns, coerce_float=coerce_float
)
break
with exit_stack:
while True:
data = result.fetchmany(chunksize)
if not data:
if not has_read_data:
yield DataFrame.from_records(
[], columns=columns, coerce_float=coerce_float
)
break

has_read_data = True
self.frame = _convert_arrays_to_dataframe(
data, columns, coerce_float, use_nullable_dtypes
)
has_read_data = True
self.frame = _convert_arrays_to_dataframe(
data, columns, coerce_float, use_nullable_dtypes
)

self._harmonize_columns(
parse_dates=parse_dates, use_nullable_dtypes=use_nullable_dtypes
)
self._harmonize_columns(
parse_dates=parse_dates, use_nullable_dtypes=use_nullable_dtypes
)

if self.index is not None:
self.frame.set_index(self.index, inplace=True)
if self.index is not None:
self.frame.set_index(self.index, inplace=True)

yield self.frame
yield self.frame

def read(
self,
Expand All @@ -1147,16 +1141,14 @@ def read(
column_names = result.keys()

if chunksize is not None:
return _cleanup_after_generator(
self._query_iterator(
result,
chunksize,
column_names,
coerce_float=coerce_float,
parse_dates=parse_dates,
use_nullable_dtypes=use_nullable_dtypes,
),
return self._query_iterator(
result,
exit_stack,
chunksize,
column_names,
coerce_float=coerce_float,
parse_dates=parse_dates,
use_nullable_dtypes=use_nullable_dtypes,
)
else:
data = result.fetchall()
Expand Down Expand Up @@ -1693,6 +1685,7 @@ def read_table(
@staticmethod
def _query_iterator(
result,
exit_stack: ExitStack,
chunksize: int,
columns,
index_col=None,
Expand All @@ -1703,31 +1696,32 @@ def _query_iterator(
):
"""Return generator through chunked result set"""
has_read_data = False
while True:
data = result.fetchmany(chunksize)
if not data:
if not has_read_data:
yield _wrap_result(
[],
columns,
index_col=index_col,
coerce_float=coerce_float,
parse_dates=parse_dates,
dtype=dtype,
use_nullable_dtypes=use_nullable_dtypes,
)
break
with exit_stack:
while True:
data = result.fetchmany(chunksize)
if not data:
if not has_read_data:
yield _wrap_result(
[],
columns,
index_col=index_col,
coerce_float=coerce_float,
parse_dates=parse_dates,
dtype=dtype,
use_nullable_dtypes=use_nullable_dtypes,
)
break

has_read_data = True
yield _wrap_result(
data,
columns,
index_col=index_col,
coerce_float=coerce_float,
parse_dates=parse_dates,
dtype=dtype,
use_nullable_dtypes=use_nullable_dtypes,
)
has_read_data = True
yield _wrap_result(
data,
columns,
index_col=index_col,
coerce_float=coerce_float,
parse_dates=parse_dates,
dtype=dtype,
use_nullable_dtypes=use_nullable_dtypes,
)

def read_query(
self,
Expand Down Expand Up @@ -1793,18 +1787,16 @@ def read_query(

if chunksize is not None:
self.returns_generator = True
return _cleanup_after_generator(
self._query_iterator(
result,
chunksize,
columns,
index_col=index_col,
coerce_float=coerce_float,
parse_dates=parse_dates,
dtype=dtype,
use_nullable_dtypes=use_nullable_dtypes,
),
return self._query_iterator(
result,
self.exit_stack,
chunksize,
columns,
index_col=index_col,
coerce_float=coerce_float,
parse_dates=parse_dates,
dtype=dtype,
use_nullable_dtypes=use_nullable_dtypes,
)
else:
data = result.fetchall()
Expand Down